1. Field of the Invention
In order to mount a transmission in front engine, front drive vehicles and four wheel drive vehicles so that the transmission is properly received in an engine volume or room, it is typical to place such a transmission and a transverse engine end to end, and to orient them both in a transverse direction of the vehicle body. In such an arrangement, the transmission is typically disposed along a line extending from an engine output shaft and in front of a front wheel drive shaft extending in a lengthwise direction of the car body.
2. Description of Related Art
For reducing an offset of the vehicle center of gravity toward the front wheels, so as to improve stability during steering and braking, it is effective to place a transverse engine and a transmission behind the front wheel drive shaft. Such a construction is described in, for example, Japanese Unexamined Patent Publication No.63(1988)-23219. Alternatively, a transmission, coupled to a transverse engine by means of a gear train, may be placed in front of the engine, above a front differential incorporated in the front wheel drive shaft, so as to transmit power to the front differential from the transmission through a transmission gear train. This type of construction is described in, for example, Japanese Unexamined Patent Publication No.56(1981)-31824. This type of transmission, which may be either manual or automatic, has input and output shafts, arranged in parallel with each other, which mount various elements for shifting speeds, or "speed shift means," thereon.
Transmission shafts, such as input and output shafts, on which the speed shift means is mounted, are disposed separately from the front differential incorporated in the front wheel drive shaft, and extend either in a lengthwise or a vertical direction of the vehicle body. Such a power train lay out requires a large space in order to be installed in the engine room, resulting in car bodies having a long nose and/or a high bonnet.
It is essential for compact cars to have a power train, including a transmission, front differential and front wheel differential, which is compact in arrangement and simple in structure. It is also essential for a compact, sophisticated power train to be provided with speed reduction means having a high speed reduction ratio.
In order for a power train to be compact in arrangement, it is effective to use a hollow transmission shaft that a front wheel drive shaft can be passed through the hollow transmission shaft. However, since a flex joint, incorporated in the front wheel drive shaft between a front differential and a front wheel, is offset towards the front wheel from the transmission, the part of the front wheel drive shaft between the flex joint and the front wheel is short in length. As is well recognized in the art, it is difficult for a short drive shaft between a flex joint and a front wheel to satisfactorily transmit an engine output to the front wheels when the wheels bump and rebound.